Analysis of interleukin 1 mediated radioprotection.

The potential value of interleukin 1 (IL-1) containing supernatants as a radioprotective agent was evaluated. It was found that the response of irradiated thymocytes to mitogens was partially restored if IL-1 containing supernatants was included in the culture medium immediately after irradiation. A delay of 24 h in the addition of IL-1 and mitogen abrogated the radioprotection effect. Under the same conditions IL-2 containing supernatants were effective, suggesting that the dose modifying effect of IL-1 acts through induction of IL-2 elaboration. The results of the present study may be important in cases where it is necessary to restore depressed immune response resulting from irradiation accidents or radiotherapy.     

Variability and predictors of urinary bisphenol A concentrations during pregnancy

Background

Prenatal bisphenol A (BPA) exposure may be associated with developmental toxicity, but few studies have examined the variability and predictors of urinary BPA concentrations during pregnancy.

Objective

Our goal was to estimate the variability and predictors of serial urinary BPA concentrations taken during pregnancy.

Methods

We measured BPA concentrations during pregnancy and at birth in three spot urine samples from 389 women. We calculated the intraclass correlation coefficient (ICC) to assess BPA variability and estimated associations between log₁₀-transformed urinary BPA concentrations and demographic, occupational, dietary, and environmental factors, using mixed models.

Results

Geometric mean (GM) creatinine-standardized concentrations (micrograms per gram) were 1.7 (16 weeks), 2.0 (26 weeks), and 2.0 (birth). Creatinine-standardized BPA concentrations exhibited low reproducibility (ICC = 0.11). By occupation, cashiers had the highest BPA concentrations (GM: 2.8 μg/g). Consuming canned vegetables at least once a day was associated with higher BPA concentrations (GM = 2.3 μg/g) compared with those consuming no canned vegetables (GM = 1.6 μg/g). BPA concentrations did not vary by consumption of fresh fruits and vegetables, canned fruit, or store-bought fresh and frozen fish. Urinary high-molecular-weight phthalate and serum tobacco smoke metabolite concentrations were positively associated with BPA concentrations.

Conclusions

These results suggest numerous sources of BPA exposure during pregnancy. Etiological studies may need to measure urinary BPA concentrations more than once during pregnancy and adjust for phthalates and tobacco smoke exposures.     

Selecting Adequate Exposure Biomarkers of Diisononyl and Diisodecyl Phthalates: Data from the 2005–2006 National Health and Nutrition Examination Survey

Background

High-molecular-weight phthalates, such as diisononyl phthalate (DINP) and diisodecyl phthalate (DIDP), are used primarily as polyvinyl chloride plasticizers.

Objectives

We assessed exposure to DINP and DIDP in a representative sample of persons ≥ 6 years of age in the U.S. general population from the 2005–2006 National Health and Nutrition Examination Survey (NHANES).

Methods

We analyzed 2,548 urine samples by using online solid-phase extraction coupled to isotope dilution high-performance liquid chromatography–tandem mass spectrometry.

Results

We detected monocarboxyisooctyl phthalate (MCOP), a metabolite of DINP, and monocarboxyisononyl phthalate (MCNP), a metabolite of DIDP, in 95.2% and 89.9% of the samples, respectively. We detected monoisononyl phthalate (MNP), a minor metabolite of DINP, much less frequently (12.9%) and at concentration ranges (> 0.8 μg/L–148.1 μg/L) much lower than MCOP (> 0.7 μg/L– 4,961 μg/L). Adjusted geometric mean concentrations of MCOP and MCNP were significantly higher (p < 0.01) among children than among adolescents and adults.

Conclusions

The general U.S. population, including children, was exposed to DINP and DIDP. In previous NHANES cycles, the occurrence of human exposure to DINP by using MNP as the sole urinary biomarker has been underestimated, thus illustrating the importance of selecting the most adequate biomarkers for exposure assessment.     

Quantitative detection of nine phthalate metabolites in human serum using reversed-phase high-performance liquid chromatography-electrospray ionization-tandem mass spectrometry

We developed a highly sensitive method for the quantitative detection of nine phthalate ester metabolites in human serum. This method requires denaturation of the serum enzymes immediately after blood collection to avoid the hydrolysis of the contaminant diester parent compounds introduced during blood collection and storage. Before analysis, the samples were subjected to an enzymatic deconjugation to hydrolyze the glucuronidated phthalate monoesters and a solid-phase extraction to isolate the monoesters from other serum components. The extracts were analyzed using reversed-phase high-performance liquid chromatography-electrospray ionization-tandem mass spectrometry. The limits of detection of all nine phthalate monoesters in serum were in the low nanogram-per-milliliter range (0.6-1.3 ng/mL). Stable isotope-labeled internal standards for all analytes were used to improve precision and for recovery corrections. This highly selective method permits the analysis of phthalate monoesters without interferences resulting from the hydrolysis of the ubiquitous contaminant phthalate diesters by serum enzymes. In addition, it allows the direct measurement of the active phthalate monoester metabolites reportedly responsible for the reproductive and developmental toxicity of certain phthalates.     

Mono(2-ethyl-5-hydroxyhexyl) phthalate and mono-(2-ethyl-5-oxohexyl) phthalate as biomarkers for human exposure assessment to di-(2-ethylhexyl) phthalate

Exposure to di-(2-ethylhexyl) phthalate (DEHP) is prevalent based on the measurement of its hydrolytic metabolite mono-(2-ethylhexyl) phthalate (MEHP) in the urine of 78% of the general U.S. population studied in the 1999-2000 National Health and Nutrition Examination Survey (NHANES). However, despite the high level of production and use of DEHP, the urinary MEHP levels in the NHANES samples were lower than the monoester metabolites of phthalates less commonly used than DEHP, suggesting metabolic differences between phthalates. We measured MEHP and two oxidative DEHP metabolites, mono-(2-ethyl-5-oxohexyl) phthalate (MEOHP) and mono (2-ethyl-5-hydroxyhexyl) phthalate (MEHHP) to verify whether these other metabolites account for a greater proportion of DEHP metabolic products in 127 paired human urine and serum samples. We found that the urinary levels of MEHHP and MEOHP were 10-fold higher than levels of MEHP; concentrations of urinary MEOHP and MEHHP were strongly correlated (r = 0.928). We also found that the serum levels of MEOHP and MEHHP were comparatively lower than those in urine. Furthermore, the glucuronide-bound conjugates of the oxidative metabolites were the predominant form in both urine and serum. MEOHP and MEHHP cannot be formed by serum enzymes from the hydrolysis of any contamination from DEHP potentially introduced during blood collection and storage. Therefore, concentrations of MEHHP and MEOHP in serum may be a more selective measure of DEHP exposure than is MEHP. However, additional data on the absorption, distribution, metabolism, and elimination of these oxidative metabolites are needed to completely understand the extent of DEHP exposure from the serum concentrations of oxidative DEHP metabolites.     

Expression of p16INK4A in gastrointestinal stromal tumours (GISTs): two different forms exist that independently correlate with poor prognosis

Haller F, Agaimy A, Cameron S, Beyer M, Gunawan B, Happel N, Langer C, Ramadori G, von Heydebreck A & Füzesi L
(2010) Histopathology 56, 305–318 Expression of p16 ^INK4A in gastrointestinal stromal tumours (GISTs): two different forms exist that independently correlate with poor prognosis Aims: To determine the prognostic impact of p16^INK4A expression in gastrointestinal stromal tumours (GISTs), which is currently being questioned, with both loss and overexpression said to be correlated with poor prognosis. Methods and results: Two different forms of p16^INK4A were identified, presenting with predominantly nuclear and cytoplasmic expression pattern, respectively. The immunohistochemical expression of the two forms and their correlation with E2F1 and prognosis were analysed in a series of 120 GISTs with clinical follow‐up. Low nuclear p16^INK4A expression correlated with E2F1 up‐regulation, higher mitotic counts, and tumour progression. The prognostic value of nuclear p16^INK4A expression was only marginally significant (P = 0.05). Strong expression of the cytoplasmic p16^INK4A form was significantly associated with shorter disease‐free survival (P = 2 × 10^?5). The prognostic impact of strong expression of the cytoplasmic p16^INK4A form was independent of anatomical localization, tumour size and mitotic counts, and significant even among the cohort of tumours with high malignant potential. Conclusions: Low expression of the nuclear p16^INK4A form and strong expression of the cytoplasmic p16^INK4A form both represent two independent parameters each associated with tumour progression in GISTs. Low nuclear p16^INK4A expression enables E2F1 up‐regulation and consecutive accelerated cell proliferation. In contrast, strong cytoplasmic p16^INK4A expression probably reflects a negative feedback loop as a result of (as yet unknown) oncogenic events.     

Effect of radiation on the production of interleukins and T-lymphocyte activities

The effect of 0-400 rad 60Co gamma-ray doses on distinct steps in the process of murine T-cell activation by concanavalin A (Con A) was investigated. When C57BL/6 spleen cells were stimulated immediately after irradiation, production of interleukin-1 (IL-1) and interleukin-2 (IL-2) was not impaired. Concomitantly, the display of IL-2 receptors in Con A-induced reactivity to IL-2 was not affected. The proliferative response was markedly diminished by increasing doses of radiation. The effect of radiation was found to depend not only on the delivered dose but also on the time interval between irradiation and stimulation of the lymphoid cultures. When the mitogenic stimulus was delayed for 24 hours following irradiation, IL-1 production was not diminished, whereas IL-2 production was impaired by doses greater than 200 rad. The proliferative response was diminished to a markedly higher degree as compared to the degree it was diminished in cell cultures stimulated by Con A immediately after irradiation. IL-2 production and the proliferative response to Con A of irradiated cell suspensions, cultured without mitogen for 24 hours post irradiation, were also assessed after adjustment for cell death. In this case, an impairment in IL-2 production that was dose dependent was apparent, but still the levels of IL-2 secreted by 400-rad irradiated cells reached high levels. In contrast, the proliferative response to Con A could not be restored. When T-cell growth factor was added concomitantly with Con A to irradiated cell cultures, a radioprotective effect could be observed.